AT89C51RB2-SLRUL [Microchip]

High-performance, 8-bit microcontroller with 16KB flash. It retains all features of the 80C52 with 256 Bytes of internal RAM, a 9-source 4-level interrupt controller, and three timer/counters.

It features a programmable counter array, an XRAM of 1024 bytes, hardware watchdog timer, keyboard interface, SPI interface, versatile serial channel that facilitates multiprocessor communication (EUART), and a speed improvement mechanism (X2 mode).

Implementing an external brown-out is recommended to prevent any flash/EEPROM corruption during power-on or power-off.